define([
	'lodash'
], function (_) {
	'use strict';

	// This is auto generated from the unicode tables.
	// The tables are at:
	// http://www.fileformat.info/info/unicode/category/Lu/list.htm
	// http://www.fileformat.info/info/unicode/category/Ll/list.htm
	// http://www.fileformat.info/info/unicode/category/Lt/list.htm
	// http://www.fileformat.info/info/unicode/category/Lm/list.htm
	// http://www.fileformat.info/info/unicode/category/Lo/list.htm
	// http://www.fileformat.info/info/unicode/category/Nl/list.htm

	var unicodeLetterTable = [
		170, 170, 181, 181, 186, 186, 192, 214,
		216, 246, 248, 705, 710, 721, 736, 740, 748, 748, 750, 750,
		880, 884, 886, 887, 890, 893, 902, 902, 904, 906, 908, 908,
		910, 929, 931, 1013, 1015, 1153, 1162, 1319, 1329, 1366,
		1369, 1369, 1377, 1415, 1488, 1514, 1520, 1522, 1568, 1610,
		1646, 1647, 1649, 1747, 1749, 1749, 1765, 1766, 1774, 1775,
		1786, 1788, 1791, 1791, 1808, 1808, 1810, 1839, 1869, 1957,
		1969, 1969, 1994, 2026, 2036, 2037, 2042, 2042, 2048, 2069,
		2074, 2074, 2084, 2084, 2088, 2088, 2112, 2136, 2308, 2361,
		2365, 2365, 2384, 2384, 2392, 2401, 2417, 2423, 2425, 2431,
		2437, 2444, 2447, 2448, 2451, 2472, 2474, 2480, 2482, 2482,
		2486, 2489, 2493, 2493, 2510, 2510, 2524, 2525, 2527, 2529,
		2544, 2545, 2565, 2570, 2575, 2576, 2579, 2600, 2602, 2608,
		2610, 2611, 2613, 2614, 2616, 2617, 2649, 2652, 2654, 2654,
		2674, 2676, 2693, 2701, 2703, 2705, 2707, 2728, 2730, 2736,
		2738, 2739, 2741, 2745, 2749, 2749, 2768, 2768, 2784, 2785,
		2821, 2828, 2831, 2832, 2835, 2856, 2858, 2864, 2866, 2867,
		2869, 2873, 2877, 2877, 2908, 2909, 2911, 2913, 2929, 2929,
		2947, 2947, 2949, 2954, 2958, 2960, 2962, 2965, 2969, 2970,
		2972, 2972, 2974, 2975, 2979, 2980, 2984, 2986, 2990, 3001,
		3024, 3024, 3077, 3084, 3086, 3088, 3090, 3112, 3114, 3123,
		3125, 3129, 3133, 3133, 3160, 3161, 3168, 3169, 3205, 3212,
		3214, 3216, 3218, 3240, 3242, 3251, 3253, 3257, 3261, 3261,
		3294, 3294, 3296, 3297, 3313, 3314, 3333, 3340, 3342, 3344,
		3346, 3386, 3389, 3389, 3406, 3406, 3424, 3425, 3450, 3455,
		3461, 3478, 3482, 3505, 3507, 3515, 3517, 3517, 3520, 3526,
		3585, 3632, 3634, 3635, 3648, 3654, 3713, 3714, 3716, 3716,
		3719, 3720, 3722, 3722, 3725, 3725, 3732, 3735, 3737, 3743,
		3745, 3747, 3749, 3749, 3751, 3751, 3754, 3755, 3757, 3760,
		3762, 3763, 3773, 3773, 3776, 3780, 3782, 3782, 3804, 3805,
		3840, 3840, 3904, 3911, 3913, 3948, 3976, 3980, 4096, 4138,
		4159, 4159, 4176, 4181, 4186, 4189, 4193, 4193, 4197, 4198,
		4206, 4208, 4213, 4225, 4238, 4238, 4256, 4293, 4304, 4346,
		4348, 4348, 4352, 4680, 4682, 4685, 4688, 4694, 4696, 4696,
		4698, 4701, 4704, 4744, 4746, 4749, 4752, 4784, 4786, 4789,
		4792, 4798, 4800, 4800, 4802, 4805, 4808, 4822, 4824, 4880,
		4882, 4885, 4888, 4954, 4992, 5007, 5024, 5108, 5121, 5740,
		5743, 5759, 5761, 5786, 5792, 5866, 5870, 5872, 5888, 5900,
		5902, 5905, 5920, 5937, 5952, 5969, 5984, 5996, 5998, 6000,
		6016, 6067, 6103, 6103, 6108, 6108, 6176, 6263, 6272, 6312,
		6314, 6314, 6320, 6389, 6400, 6428, 6480, 6509, 6512, 6516,
		6528, 6571, 6593, 6599, 6656, 6678, 6688, 6740, 6823, 6823,
		6917, 6963, 6981, 6987, 7043, 7072, 7086, 7087, 7104, 7141,
		7168, 7203, 7245, 7247, 7258, 7293, 7401, 7404, 7406, 7409,
		7424, 7615, 7680, 7957, 7960, 7965, 7968, 8005, 8008, 8013,
		8016, 8023, 8025, 8025, 8027, 8027, 8029, 8029, 8031, 8061,
		8064, 8116, 8118, 8124, 8126, 8126, 8130, 8132, 8134, 8140,
		8144, 8147, 8150, 8155, 8160, 8172, 8178, 8180, 8182, 8188,
		8305, 8305, 8319, 8319, 8336, 8348, 8450, 8450, 8455, 8455,
		8458, 8467, 8469, 8469, 8473, 8477, 8484, 8484, 8486, 8486,
		8488, 8488, 8490, 8493, 8495, 8505, 8508, 8511, 8517, 8521,
		8526, 8526, 8544, 8584, 11264, 11310, 11312, 11358,
		11360, 11492, 11499, 11502, 11520, 11557, 11568, 11621,
		11631, 11631, 11648, 11670, 11680, 11686, 11688, 11694,
		11696, 11702, 11704, 11710, 11712, 11718, 11720, 11726,
		11728, 11734, 11736, 11742, 11823, 11823, 12293, 12295,
		12321, 12329, 12337, 12341, 12344, 12348, 12353, 12438,
		12445, 12447, 12449, 12538, 12540, 12543, 12549, 12589,
		12593, 12686, 12704, 12730, 12784, 12799, 13312, 13312,
		19893, 19893, 19968, 19968, 40907, 40907, 40960, 42124,
		42192, 42237, 42240, 42508, 42512, 42527, 42538, 42539,
		42560, 42606, 42623, 42647, 42656, 42735, 42775, 42783,
		42786, 42888, 42891, 42894, 42896, 42897, 42912, 42921,
		43002, 43009, 43011, 43013, 43015, 43018, 43020, 43042,
		43072, 43123, 43138, 43187, 43250, 43255, 43259, 43259,
		43274, 43301, 43312, 43334, 43360, 43388, 43396, 43442,
		43471, 43471, 43520, 43560, 43584, 43586, 43588, 43595,
		43616, 43638, 43642, 43642, 43648, 43695, 43697, 43697,
		43701, 43702, 43705, 43709, 43712, 43712, 43714, 43714,
		43739, 43741, 43777, 43782, 43785, 43790, 43793, 43798,
		43808, 43814, 43816, 43822, 43968, 44002, 44032, 44032,
		55203, 55203, 55216, 55238, 55243, 55291, 63744, 64045,
		64048, 64109, 64112, 64217, 64256, 64262, 64275, 64279,
		64285, 64285, 64287, 64296, 64298, 64310, 64312, 64316,
		64318, 64318, 64320, 64321, 64323, 64324, 64326, 64433,
		64467, 64829, 64848, 64911, 64914, 64967, 65008, 65019,
		65136, 65140, 65142, 65276, 65313, 65338, 65345, 65370,
		65382, 65470, 65474, 65479, 65482, 65487, 65490, 65495,
		65498, 65500, 65536, 65547, 65549, 65574, 65576, 65594,
		65596, 65597, 65599, 65613, 65616, 65629, 65664, 65786,
		65856, 65908, 66176, 66204, 66208, 66256, 66304, 66334,
		66352, 66378, 66432, 66461, 66464, 66499, 66504, 66511,
		66513, 66517, 66560, 66717, 67584, 67589, 67592, 67592,
		67594, 67637, 67639, 67640, 67644, 67644, 67647, 67669,
		67840, 67861, 67872, 67897, 68096, 68096, 68112, 68115,
		68117, 68119, 68121, 68147, 68192, 68220, 68352, 68405,
		68416, 68437, 68448, 68466, 68608, 68680, 69635, 69687,
		69763, 69807, 73728, 74606, 74752, 74850, 77824, 78894,
		92160, 92728, 110592, 110593, 119808, 119892, 119894, 119964,
		119966, 119967, 119970, 119970, 119973, 119974, 119977, 119980,
		119982, 119993, 119995, 119995, 119997, 120003, 120005, 120069,
		120071, 120074, 120077, 120084, 120086, 120092, 120094, 120121,
		120123, 120126, 120128, 120132, 120134, 120134, 120138, 120144,
		120146, 120485, 120488, 120512, 120514, 120538, 120540, 120570,
		120572, 120596, 120598, 120628, 120630, 120654, 120656, 120686,
		120688, 120712, 120714, 120744, 120746, 120770, 120772, 120779,
		131072, 131072, 173782, 173782, 173824, 173824, 177972, 177972,
		177984, 177984, 178205, 178205, 194560, 195101
	];

	var identifierStartTable = [];

	for (var i = 0; i < 128; i++) {
		identifierStartTable[i] =
			i >= 48 && i <= 57 || // 0-9
			i === 36 ||           // $
			i >= 65 && i <= 90 || // A-Z
			i === 95 ||           // _
			i === 45 ||           // -
			i === 42 ||           // *
			i === 58 ||           // :
			i === 91 ||           // templateStart [
			i === 93 ||           // templateEnd ]
			i === 63 ||           // ?
			i === 37 ||           // %
			i === 35 ||           // #
			i === 61 ||           // =
			i >= 97 && i <= 122;  // a-z
	}

	var identifierPartTable = [];

	for (var i2 = 0; i2 < 128; i2++) {
		identifierPartTable[i2] =
			identifierStartTable[i2] || // $, _, A-Z, a-z
			i2 >= 48 && i2 <= 57;        // 0-9
	}

	function Lexer(expression) {
		this.input = expression;
		this.char = 1;
		this.from = 1;
	}

	Lexer.prototype = {

		peek: function (i) {
			return this.input.charAt(i || 0);
		},

		skip: function (i) {
			i = i || 1;
			this.char += i;
			this.input = this.input.slice(i);
		},

		tokenize: function () {
			var list = [];
			var token;
			while (token = this.next()) {
				list.push(token);
			}
			return list;
		},

		next: function () {
			this.from = this.char;

			// Move to the next non-space character.
			var start;
			if (/\s/.test(this.peek())) {
				start = this.char;

				while (/\s/.test(this.peek())) {
					this.from += 1;
					this.skip();
				}

				if (this.peek() === "") { // EOL
					return null;
				}
			}

			var match = this.scanStringLiteral();
			if (match) {
				return match;
			}

			match =
				this.scanPunctuator() ||
				this.scanNumericLiteral() ||
				this.scanIdentifier() ||
				this.scanTemplateSequence();

			if (match) {
				this.skip(match.value.length);
				return match;
			}

			// No token could be matched, give up.
			return null;
		},

		scanTemplateSequence: function () {
			if (this.peek() === '[' && this.peek(1) === '[') {
				return {
					type: 'templateStart',
					value: '[[',
					pos: this.char
				};
			}

			if (this.peek() === ']' && this.peek(1) === ']') {
				return {
					type: 'templateEnd',
					value: '[[',
					pos: this.char
				};
			}

			return null;
		},

		/*
		 * Extract a JavaScript identifier out of the next sequence of
		 * characters or return 'null' if its not possible. In addition,
		 * to Identifier this method can also produce BooleanLiteral
		 * (true/false) and NullLiteral (null).
		 */
		scanIdentifier: function () {
			var id = "";
			var index = 0;
			var type, char;

			// Detects any character in the Unicode categories "Uppercase
			// letter (Lu)", "Lowercase letter (Ll)", "Titlecase letter
			// (Lt)", "Modifier letter (Lm)", "Other letter (Lo)", or
			// "Letter number (Nl)".
			//
			// Both approach and unicodeLetterTable were borrowed from
			// Google's Traceur.

			function isUnicodeLetter(code) {
				for (var i = 0; i < unicodeLetterTable.length;) {
					if (code < unicodeLetterTable[i++]) {
						return false;
					}

					if (code <= unicodeLetterTable[i++]) {
						return true;
					}
				}

				return false;
			}

			function isHexDigit(str) {
				return (/^[0-9a-fA-F]$/).test(str);
			}

			var readUnicodeEscapeSequence = _.bind(function () {
				/*jshint validthis:true */
				index += 1;

				if (this.peek(index) !== "u") {
					return null;
				}

				var ch1 = this.peek(index + 1);
				var ch2 = this.peek(index + 2);
				var ch3 = this.peek(index + 3);
				var ch4 = this.peek(index + 4);
				var code;

				if (isHexDigit(ch1) && isHexDigit(ch2) && isHexDigit(ch3) && isHexDigit(ch4)) {
					code = parseInt(ch1 + ch2 + ch3 + ch4, 16);

					if (isUnicodeLetter(code)) {
						index += 5;
						return "\\u" + ch1 + ch2 + ch3 + ch4;
					}

					return null;
				}

				return null;
			}, this);

			var getIdentifierStart = _.bind(function () {
				/*jshint validthis:true */
				var chr = this.peek(index);
				var code = chr.charCodeAt(0);

				if (chr === '*') {
					index += 1;
					return chr;
				}

				if (code === 92) {
					return readUnicodeEscapeSequence();
				}

				if (code < 128) {
					if (identifierStartTable[code]) {
						index += 1;
						return chr;
					}

					return null;
				}

				if (isUnicodeLetter(code)) {
					index += 1;
					return chr;
				}

				return null;
			}, this);

			var getIdentifierPart = _.bind(function () {
				/*jshint validthis:true */
				var chr = this.peek(index);
				var code = chr.charCodeAt(0);

				if (code === 92) {
					return readUnicodeEscapeSequence();
				}

				if (code < 128) {
					if (identifierPartTable[code]) {
						index += 1;
						return chr;
					}

					return null;
				}

				if (isUnicodeLetter(code)) {
					index += 1;
					return chr;
				}

				return null;
			}, this);

			char = getIdentifierStart();
			if (char === null) {
				return null;
			}

			id = char;
			for (; ;) {
				char = getIdentifierPart();

				if (char === null) {
					break;
				}

				id += char;
			}

			switch (id) {
				default:
					type = "identifier";
			}

			return {
				type: type,
				value: id,
				pos: this.char
			};

		},

		/*
		 * Extract a numeric literal out of the next sequence of
		 * characters or return 'null' if its not possible. This method
		 * supports all numeric literals described in section 7.8.3
		 * of the EcmaScript 5 specification.
		 *
		 * This method's implementation was heavily influenced by the
		 * scanNumericLiteral function in the Esprima parser's source code.
		 */
		scanNumericLiteral: function () {
			var index = 0;
			var value = "";
			var length = this.input.length;
			var char = this.peek(index);
			var bad;

			function isDecimalDigit(str) {
				return (/^[0-9]$/).test(str);
			}

			function isOctalDigit(str) {
				return (/^[0-7]$/).test(str);
			}

			function isHexDigit(str) {
				return (/^[0-9a-fA-F]$/).test(str);
			}

			function isIdentifierStart(ch) {
				return (ch === "$") || (ch === "_") || (ch === "\\") ||
					(ch >= "a" && ch <= "z") || (ch >= "A" && ch <= "Z");
			}

			// handle negative num literals
			if (char === '-') {
				value += char;
				index += 1;
				char = this.peek(index);
			}

			// Numbers must start either with a decimal digit or a point.
			if (char !== "." && !isDecimalDigit(char)) {
				return null;
			}

			if (char !== ".") {
				value += this.peek(index);
				index += 1;
				char = this.peek(index);

				if (value === "0") {
					// Base-16 numbers.
					if (char === "x" || char === "X") {
						index += 1;
						value += char;

						while (index < length) {
							char = this.peek(index);
							if (!isHexDigit(char)) {
								break;
							}
							value += char;
							index += 1;
						}

						if (value.length <= 2) { // 0x
							return {
								type: 'number',
								value: value,
								isMalformed: true,
								pos: this.char
							};
						}

						if (index < length) {
							char = this.peek(index);
							if (isIdentifierStart(char)) {
								return null;
							}
						}

						return {
							type: 'number',
							value: value,
							base: 16,
							isMalformed: false,
							pos: this.char
						};
					}

					// Base-8 numbers.
					if (isOctalDigit(char)) {
						index += 1;
						value += char;
						bad = false;

						while (index < length) {
							char = this.peek(index);

							// Numbers like '019' (note the 9) are not valid octals
							// but we still parse them and mark as malformed.

							if (isDecimalDigit(char)) {
								bad = true;
							} else if (!isOctalDigit(char)) {
								break;
							}
							value += char;
							index += 1;
						}

						if (index < length) {
							char = this.peek(index);
							if (isIdentifierStart(char)) {
								return null;
							}
						}

						return {
							type: 'number',
							value: value,
							base: 8,
							isMalformed: false
						};
					}

					// Decimal numbers that start with '0' such as '09' are illegal
					// but we still parse them and return as malformed.

					if (isDecimalDigit(char)) {
						index += 1;
						value += char;
					}
				}

				while (index < length) {
					char = this.peek(index);
					if (!isDecimalDigit(char)) {
						break;
					}
					value += char;
					index += 1;
				}
			}

			// Decimal digits.

			if (char === ".") {
				value += char;
				index += 1;

				while (index < length) {
					char = this.peek(index);
					if (!isDecimalDigit(char)) {
						break;
					}
					value += char;
					index += 1;
				}
			}

			// Exponent part.

			if (char === "e" || char === "E") {
				value += char;
				index += 1;
				char = this.peek(index);

				if (char === "+" || char === "-") {
					value += this.peek(index);
					index += 1;
				}

				char = this.peek(index);
				if (isDecimalDigit(char)) {
					value += char;
					index += 1;

					while (index < length) {
						char = this.peek(index);
						if (!isDecimalDigit(char)) {
							break;
						}
						value += char;
						index += 1;
					}
				} else {
					return null;
				}
			}

			if (index < length) {
				char = this.peek(index);
				if (!this.isPunctuator(char)) {
					return null;
				}
			}

			return {
				type: 'number',
				value: value,
				base: 10,
				pos: this.char,
				isMalformed: !isFinite(value)
			};
		},

		isPunctuator: function (ch1) {
			switch (ch1) {
				case ".":
				case "(":
				case ")":
				case ",":
				case "{":
				case "}":
					return true;
			}

			return false;
		},

		scanPunctuator: function () {
			var ch1 = this.peek();

			if (this.isPunctuator(ch1)) {
				return {
					type: ch1,
					value: ch1,
					pos: this.char
				};
			}

			return null;
		},

		/*
		 * Extract a string out of the next sequence of characters and/or
		 * lines or return 'null' if its not possible. Since strings can
		 * span across multiple lines this method has to move the char
		 * pointer.
		 *
		 * This method recognizes pseudo-multiline JavaScript strings:
		 *
		 *   var str = "hello\
		 *   world";
		 */
		scanStringLiteral: function () {
			/*jshint loopfunc:true */
			var quote = this.peek();

			// String must start with a quote.
			if (quote !== "\"" && quote !== "'") {
				return null;
			}

			var value = "";

			this.skip();

			while (this.peek() !== quote) {
				if (this.peek() === "") { // End Of Line
					return {
						type: 'string',
						value: value,
						isUnclosed: true,
						quote: quote,
						pos: this.char
					};
				}

				var char = this.peek();
				var jump = 1; // A length of a jump, after we're done
							  // parsing this character.

				value += char;
				this.skip(jump);
			}

			this.skip();
			return {
				type: 'string',
				value: value,
				isUnclosed: false,
				quote: quote,
				pos: this.char
			};
		},

	};

	return Lexer;

});
